Riddle.



B. H. MUMFORD.

RIDDLE.

APPLICATION FILED MAY 1, 1907.

979,685, Patented Dec. 27, 1910.

.wl'l'flm INVENTOR ilTE F EDGAR H. MUMFORD, OF PHILADELPHIA, PENNSYLVANIA.

RIDDLE.

erases.

Specification of Letters Patent.

Application filed May 1, 1907.

Patented Dec. 27, 1910.

Serial No. 371,231.

T 0 all whom it may concern:

Be it known that l, EDGAR H. hTUIvE'FORD, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in tiddles, of which the following is a specification.

My invention relates to sand riddles or sieves for sifting the sand used in molding operations, and has for its objects: 'to pro vide a riddle wherein the sand passes through the screening more rapidly than has been the case heretofore; to provide a riddle wherein the screen is kept clean and prevented from clogging, and to make the riddle act as a stop or gate controlling the flow of sand. One form of the invention is shown in the accompanying drawings, wherein Figure 1 is a longitudinal section through my improved riddle and. the hopper and receptacle for the screened sand, and

Figure 2 is a plan view of the riddle, the hopper being removed.

Heretofore in the use of the ordinary two screen riddles some diiiiculty has been experienced in securing the desired degree of rapidity of operation, and in keeping the lower screen clean, due to the tendency of the lower layer of sand on the bottom screen to remain stationary during the backward and forward movement of the riddle, while the body of the sand moved 011 top of such lowerlayer. My invention is designed to secure the backward and forward movement of the whole body of sand including the lower layer, with respect to the screens, thus grating the sand over the lower screen, causing its rapid passage therethrough and keep ing such lower screen clean. This object I accomplish by placing tubular members endwise between the screens, thus permitting a free passage of the sand, and at the same time causing a movement of the whole body of sand between the two screens.

Referring to the drawings wherein the general arrangement of parts shown is an ordinary one in the art, 1 is a hopper to which the sand to be screened is delivered by means of an elevator 2, 3 is the riddle wherein my invention particularly resides, which riddle is reciprocably mounted in guides 4 in the usual manner and is reciprocated by means of the power cylinder 5 of ordinary construction, and 6 is the receiving member into which the screened sand falls. The riddle is provided with the ordinary upper and lower screens '7 and 8, the upper screen being coarse and the lower screen being fine, and a plurality of tubes 9 of greater diameter than length are loosely interposed between the two screens. Suflicient room is provided to permit of the backward and forward movement of these cylinders or scrapers when the riddle is reciprocated by means of the power cylinder 5. It will be seen that the backward and forward movement of the tubes 9 with respect to the screens carries with them the entire body of sand and vice versa, thus grating it over the lower screen, and causing its rapid passage therethrough.

The members 9 are made of greater diameter than height to prevent their turning sidewise between the two screens. The orifice of the hopper 1 is placed close to the upper surface of the screen whereby the screen acts as a closure or gate when not in motion.

It will be apparent that the scrapers need not be of the precise structure shown, the essentials being that they provide a cellular structure for the free passage of the sand and at the same time secure the simultaneous movement of the lower layer of sand and the layers thereabove, so that the sand is grated over the lower screen, and that their relative height and diameter be such that they will not tip over.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is the fol lowing:

1. A sand riddle comprising a pair of opposing screens and a plurality of devices interposed between the screens for grating the sand through the lower screen and comprising pipe sections of greater diameter than height with their axes at right angles to the planes of the screens and movable laterally independently of each other, the said sections having substantially their entire lower edges in engagement with the lower screen.

2. A sand riddle comprising a pair of opposing screens, and a plurality of devices interposed between the screens for grating the sand through the lower screen and comprising cellular sections of greater diameter than height each adapted to inclose a body of sand and supported upon its edge so as to permit the free passage of the sand therethrough, the said sections being movable laterally independently of each other and having the greater portion of their .lower edges in engagementwith the lower screen in order to grate the sand therethrough.

3. In combination, a receptacle provided with a feeding orifice and a gate for the orifice comprising a riddle mounted for reciprocation past the orifice and consisting of a pair of spaced screens together adapted to substantially prevent the passage of sand when the riddle is stationary, and devices interposed between the screens for grating the sand through the lower screen when the riddle is reciprocated and comprising a plurality of cellular sections each adapted to inclose a body of sand and supported upon its edge so as to permit the free passage of the sand therethrough, the said sections being movable laterally.

In testimony whereof I have hereunto signed my name in the presence of the two subscribed witnesses.

EDGAR H. MUMFORD. lVitnesses E. MELVILLE HUGGINS, CHARLES C. Norms, Jr. 

